Importance

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Abstract

A trip indicator circuit for a circuit interrupter of an electric power system, which includes an electromagnetic status indicator, having an indicator which is movable between an indicating position and a non-indicating position, a pulse-actuated set coil for moving the indicator to the indicating position, and a pulse-actuated reset coil for moving the indicator to the non-indicating position. An indicator set circuit for energizing the set coil is connected across the trip coil by an electronic switching device which is rendered conductive by an overcurrent sensing circuit whenever a particular abnormal condition occurs in the electric power system, so that the set coil will be energized only when the circuit interrupter is tripped during the occurrence of the particular abnormal condition. A reset circuit is connected across the closing coil to energize the reset coil each time the circuit interrupter is closed. The reset circuit includes a capacitor which is connected across the closing coil in series with the reset coil and a first diode which is orientated so that, when the closing coil is energized, a current pulse flows through the first diode, the capacitor, and the reset coil until the capacitor is fully charged. The reset circuit further includes a resistor connected across the first diode, and a second diode connected across the reset coil and orientated to allow the capacitor to discharge through the resistor, the closing coil, and the second diode when the closing coil is deenergized. The resistor prevents two closely-spaced resetting operations of the indicator, which otherwise may occur when the interrupter is tripped immediately after being closed.

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First Claim